CODEWITHSUNDEEP
pythonlistscipy
henry
henry

Reputation: 965

Finding ConvexHull of points

Following array:

p = np.array([[ 0,  0],
       [ 9,  0],
       [18,  0],
       [27,  0],
       [36,  0],
       [45,  0],
       [54,  0],
       [63,  0],
       [72,  0],
       [ 0,  9],
       [ 9,  9],
       [18,  9],
       [27,  9],
       [36,  9],
       [45,  9],
       [54,  9],
       [ 0, 18],
       [ 9, 18],
       [18, 18],
       [27, 18],
       [36, 18],
       [ 0, 27],
       [ 9, 27],
       [18, 27],
       [ 0, 36]])

When I try to run the example from here https://docs.scipy.org/doc/scipy/reference/generated/scipy.spatial.ConvexHull.html

from scipy.spatial import ConvexHull

import matplotlib.pyplot as plt
plt.plot(p[:,0], p[:,1], 'o')
for simplex in hull.simplices:
    plt.plot(points[simplex, 0], points[simplex, 1], 'k-')

I get:

enter image description here

I don't see the convex hull. Anyone knows why?

Upvotes: 1

Views: 116

Answers (1)

aminrd
aminrd

Reputation: 5000

With few modifications on your code, this should work:

from scipy.spatial import ConvexHull
import matplotlib.pyplot as plt

plt.plot(p[:,0], p[:,1], 'o')
hull = ConvexHull(p)
for simplex in hull.simplices:
    plt.plot(p[simplex, 0], p[simplex, 1], 'k-')

enter image description here

Upvotes: 1

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